Semiconductor processing spray coating apparatus

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of U.S. patent application Ser. No. 08/883,393, filed Jun. 26,1997, now U.S. Pat. No. 6,066,575, which is a Divisional application of Ser. No. 08/422,485, filed Apr. 12, 1995, now U.S. Pat. No. 5,658,387, which is a Continuation in Part of Ser. No. 07/,855,767, filed Mar. 18, 1992, now U.S. Pat. No. 5,431,421, which is a Continuation in Part of Ser. No. 665,942, filed Mar. 6, 1991, now U.S. Pat. No. 5,235,995. Priority is claimed to all of these applications under 35 USC §120. The above-identified applications and patents are incorporated by reference as if set forth fully herein.

TECHNICAL FIELD

This invention relates to apparatus and methods for coating semiconductor wafers, flat panel displays, data disks, microelectronic components, thin film heads for hard disk drives, and other microelectronic or semiconductor articles that must be coated with a relatively uniform confirmation coating layer over irregular surfaces.

BACKGROUND OF THE INVENTION

The production of semiconductor devices, such as semiconductor wafers, semiconductor substrates, flat panel displays, data discs and other similar articles, generally requires at least one step in which a coating must be applied in a uniform layer across a surface of the device. For instance, the production of integrated circuits frequently involves the application of a uniform coating of photoresist on a silicon wafer or substrate.

The small feature size and variety of micro-devices being produced need highly uniform coating layers to be produced. The production of micro-devices is significantly affected by current limitations associated with non-uniformity in coating layers, particularly when coating over irregular surfaces. Such irregular surfaces occur due to the micro-devices having one or more features such as vias, channels, and peaks. These features produce irregularities in the height of the surface over which the coating is being applied. These surface irregularities cause problems and limit the overall production performance and effectiveness of conventional coating apparatus and methods because the coatings cannot be applied in a sufficiently uniform manner. The coatings often fill channels, run off the peaks, and in some instances are unable to adequately fill vias. As a result, the coating layer is thickened in the channels, and thinned on the peaks Vias can either be underfilled or overfilled depending upon viscosity and feature geometry.

A common prior art technique for applying photoresist coatings involves spraying the wafer with a photoresist and then spinning the wafer. The spinning action of the wafer produces centrifugal forces which spread the liquid photoresist. However, these spin application techniques have difficulties in providing layers having good uniformity Striations are a common problem. These striations can be initiated by surface features, contaminants, or fluid properties of the coating being applied. These and other irregularities have derogatory effects on the production of micro-circuits and other micro-devices.

Prior art semiconductor coating techniques have not been able to provide thin, uniform coating layers which conform to irregularities present on the wafer or other semiconductor surface being coated Spin coating techniques produce coating layers which tend to have an approximately level or planar surface even though surface features of varying heights are contained beneath the coating. The surfaces of wafers can contain topographical height variations of 10-40 microns with associated horizontal increments of 100-500 microns. Coatings thicknesses can thus vary in the range of 5-30 microns. This creates variations in the width of lines or other critical dimensions. These variations can in turn cause significant process yield losses Thus, there is a need for improved coating apparatus and methods which can produce a coating layer onto semiconductor surfaces which is conformational to provide more uniform coating thickness, even when applied over surfaces having features of varying heights and shapes.

Prior art coating techniques have also been troubled by difficulties which arise during lithographic processes performed upon coating layers. These difficulties arise when coating thicknesses vary to a degree sufficient to cause focusing variations in the lithographic beams used to define features of a device. These problems are in particular significant when complex topographical configurations are used. This increased difficulty occurs due to the greater difficulty in producing uniform coating thicknesses on complex topographical configurations.

Prior art semiconductor coating equipment and techniques have also been deficient in not providing uniform application of relatively viscous coating materials. The exact mechanism causing the difficulties are not fully understood. This problem of coating with viscous coatings is further exacerbated when the surface being coated is irregular, such as discussed above.

The application of coatings to semiconductor article surfaces is further complicated by the extraordinarily low levels of contamination which must be maintained when processing semiconductor materials. Contaminating particles will cause defects to exist in the resulting products and will typically decrease device yields and profitability. Thus there is a strong need to produce uniform coating layers free from contaminants or congealed particulate accumulations which may form from the coating materials themselves.

Another problem associated with present equipment and methods for coating semiconductor wafers and similar devices is that a relatively large volume of coating material is used. This occurs in some instances because the coating is applied and the wafer is spun to provide centrifugal dispersion of the coating across the wafer surface. This leads to coating material being spun off and wasted. In other equipment the coating spray is not efficiently applied and is wasted in part as an aerosol of coating particles which do not adhere to the surface being coated.

A further problem associated with current techniques is inefficient coating application equipment and techniques. The excess coating material is either wasted, or else time and money are expended to dispose of, reformulate, or recycle the spent coating material. Thus there is a continuing need for methods and apparatus which can more precisely coat such articles using a relatively smaller amount of coating material and with reduced waste.

For these and other reasons, there is a strong need for improved methods and apparatus which can provide a uniform coating layer on irregular semiconductor article surfaces using reduced amounts of the coating materials.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the accompanying drawings, which are briefly described below.

FIG. 1 is a front elevational view showing a preferred wafer spray coating and processing system made in accordance with the concepts of this invention.

FIG. 2 is a top view showing the system of FIG. <b>1</b>. Portions have been removed to better show features of the invention.

FIG. 3 is a side sectional view showing portions of a spray processing vessel bowl used in the system of FIG. 1. A spray processing vessel head is shown in phantom lines.

FIG. 4 is a side sectional view of the spray processing vessel head shown in phantom in FIG. <b>3</b>. The section line is taken along a cutting plane which changes at the centerline of the rotating assembly to better show internal components.

FIG. 5 is a top view of the spray processing vessel bowl shown in FIG. <b>3</b>.

FIG. 6 is a front elevational view of a thermal treatment station used in the system of FIG. <b>1</b>.

FIG. 7 is a top view of a one thermal treatment unit used in the thermal treatment station shown in FIG. <b>6</b>.

FIG. 8 is a sectional view along section line <b>8</b>—<b>8</b> of FIG. <b>7</b>.

FIG. 9 is a top view of an alternative spray-head having multiple nozzles.

FIG. 10 is a schematic diagram showing fluid components associated with the spray coating station.

FIG. 11 is a schematic block diagram showing control system components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).

System Generally

FIG. 1 shows a preferred semiconductor spray coating processing system <b>10</b> built in accordance with the novel concepts of this invention. Processing system <b>10</b> includes a frame or framework <b>11</b> upon which other components are mounted. Framework <b>11</b> and remaining portions of the processor are advantageously supported on rollable casters <b>14</b>.

Framework <b>11</b> is advantageously constructed so as to provide a control side or section <b>12</b> and a wafer processing side or section <b>13</b>. The processing side has a processing compartment <b>15</b> which encloses a work space. Processing compartment <b>15</b> includes several system stations which receive and process semiconductor substrates, semiconductor wafers, flat panel displays, data disks, and other semiconductor products or articles requiring ultra-low contamination processing. The processing accomplished by processing system <b>10</b> includes spraying a desired coating upon the articles. Below the processing compartment <b>15</b> is an equipment storage compartment <b>16</b> wherein various components of the system and consumable supplies, such as liquid coating materials are stored.

Processor <b>10</b> includes a front <b>18</b> which has several removable access panels <b>28</b> which are detachable from frame <b>11</b> by opening catches <b>29</b>. Similar panels are used on the sides <b>20</b> and <b>22</b>, and back <b>21</b> of the processor. Processor <b>10</b> also includes a top <b>19</b>. The top processing side has been removed in the view shown in FIG. <b>2</b>. This top panel preferably has a window (not shown) for viewing into the processing compartment.

FIG. 1 shows that the processing side <b>13</b> further has an access door <b>24</b> which is pivotally connected to a front panel of the processing compartment using hinges <b>26</b>. Door <b>24</b> preferably has a view window <b>25</b> or operator observation of the processes being performed within processing compartment <b>15</b> during operation.

FIG. 1 also shows frontal portions of the control side <b>12</b> of processor <b>10</b>. Primary portions of a control subsystem <b>30</b> is mounted within control side <b>12</b>. Illustrated components include a display <b>31</b> which is a touch screen cathode ray tube, known in the art. A data disk drive <b>32</b> is mounted below the display. A keyboard connection port <b>34</b> allows a keyboard to be connected for purposes of programming the controller. An emergency stop button <b>33</b> is mounted for easy access to allow the operator to stop operation of the machine for any reason. The control subsystem <b>30</b> includes a computer or other central controller <b>300</b> such as typically used in a variety of offices and industrial control situations. The control system computer <b>300</b> interfaces through connection wiring and in some cases related electronic subcircuits to both monitor system operation and provide operational control signals. FIG. 11 shows the relationships in a schematic diagram The specific control scheme used can vary significantly according to well-known digital control options available to provide the operational capabilities described below in greater detail.

FIG. 2 shows the top of processor <b>10</b>. The processing compartment <b>15</b> is shown with the top cover <b>27</b> removed for purposes of illustration. The processing compartment top cover <b>27</b> also includes an exhaust port <b>48</b> (FIG. 1) through which gases emanating from the processing compartment can be withdrawn, such as to a facilities exhaust line (not shown).

Wafer Transfer

FIG. 2 includes a processing compartment deck <b>23</b>. Deck <b>23</b> is supported by the framework and in part supports various components which are mounted in or adjacent to the processing compartment. As shown, deck <b>23</b> mounts a robotic wafer transfer station <b>41</b>. Wafer transfer station <b>41</b> has a base <b>64</b> which is mounted upon deck <b>23</b>. The wafer transfer mechanism also includes a first arm <b>65</b> which is pivotally connected to base <b>64</b> at a proximate end of the first arm. Arm <b>65</b> is vertically adjustable relative to the base using an extension cylinder <b>42</b>. A second arm <b>66</b> has a proximate end which is pivotally connected to the distal end of first arm <b>65</b>. The distal end of second arm <b>66</b> carries a wafer engagement tool <b>67</b>. The wafer engagement tool is preferably mounted to allow pivotal action of the engagement tool relative to the distal end of second arm <b>66</b>. The wafer engagement tool is advantageously a vacuum assisted end effector which is inserted beneath a wafer and applies a vacuum to the wafer backside to hold the wafer in position upon the palm or upper face of the engagement tool. The application of vacuum to the wafer is controlled between applied and released conditions to facilitate holding and release of the wafer.

Wafer Input and Output Stations

Also mounted upon deck <b>23</b> are a wafer input station <b>43</b> and a wafer output station <b>44</b>. Stations <b>43</b> and <b>44</b> inventory wafers being processed. Input station <b>43</b> holds an input wafer carrier <b>57</b> which contains a group of wafers which have been placed into the processing compartment for treatment. Output station <b>44</b> holds an output wafer carrier <b>58</b> which holds wafers which have been treated. FIG. 2 also shows a spray coating process station <b>40</b> and a thermal treatment station <b>46</b>.

Introduction to Process

The processing of wafers through processor <b>10</b> can be generally understood from FIG. 2 which will now be described. Wafers are fed to the system by opening processing compartment access door <b>24</b> and inserting input wafer cassette <b>57</b> loaded with wafers to be processed. The loading is typically done by manual insertion. As shown, the wafer cassette is oriented with the wafers in horizontal position. Wafers are individually removed from the input station wafer cassette <b>57</b> by the robotic wafer transfer mechanism <b>41</b>. The wafers are transferred to the spray coating station <b>40</b>. In the spray coating station the wafers are spray coated according to the processes more fully explained below.

Wafer transfer <b>41</b> then removes the wafers from the spray coating station <b>40</b> and moves them to the thermal treatment station <b>46</b>. In the thermal treatment station the wafers are most preferably heated to a desired heat treatment temperature and then cooled to a desired cold treatment temperature. In the preferred thermal treatment station <b>46</b>, the heat treatment and cold treatment are carried out in distinct thermal treatment chambers. The wafer transfer mechanism <b>41</b> moves the individual wafers between the heating and cooling chambers within station <b>46</b>.

After thermal treatment, the wafers are removed from thermal station <b>46</b> by wafer transfer <b>41</b>. The spray coated and thermally treated wafers are then moved to the output wafer cassette <b>58</b>. When the batch of wafers have been processed, the output cassette is removed via access door <b>24</b> and the processor <b>10</b> is ready to process another batch of wafers.

Spray Coating Station

FIG. 3 shows portions of the spray coating station <b>40</b> in greater detail. The spray coating station includes a processing head assembly <b>49</b> which supports and rotates a wafer <b>50</b> being processed. The processing head is described in greater detail below, particularly in connection with FIG. <b>4</b>. The processing head is constructed to mate with a spray processing vessel bowl <b>51</b> to form a spray coating spray processing vessel <b>56</b>. In the closed arrangement shown in FIG. 3, the processing head and processing bowl define a substantially enclosed processing chamber <b>63</b>.

Processing head <b>49</b> is movable upwardly from the closed position shown in FIG. 3 to allow access through a processing bowl top opening <b>59</b> through which wafer <b>50</b> and portions of the processing head are lowered. Processing head <b>49</b> is most preferably supported by a processing head shaft <b>80</b>. Processing head shaft <b>80</b> is operated by a processing head operator <b>131</b> (see FIG. 2) to both raise and lower the processing head. Processing head operator <b>131</b> is most preferably capable of both vertical motion and pivotal motion which causes shaft <b>80</b> to turn the processing head in a reciprocal manner between face-up and face-down positions. When the processing head is turned into a face-up position (not shown), the wafer <b>50</b> is positioned into the processing head with the wafer face-up. This is in comparison to the face-down position shown in FIG. <b>3</b>. The back side of wafer <b>50</b> is adjacent to the processing head.

Spray Coating Station—Processing Vessel Bowl

FIG. 3 shows that the preferred processing vessel bowl portion <b>51</b> has a sidewall <b>52</b>. Sidewall <b>52</b> is preferably cylindrical. As shown, the upper edge of the sidewall is provided with a top opening flange <b>54</b> which surrounds and defines top opening <b>59</b>. Flange <b>54</b> is provided with a seal groove <b>55</b> which receives a suitable seal, such as an O-ring seal, therein for sealing between the processing head <b>49</b> and the processing vessel base or bowl <b>51</b>.

Sidewall <b>52</b> is advantageously provided with a plurality of chamber cleaning nozzles <b>82</b> and <b>84</b>. Nozzles <b>82</b> and <b>84</b> are preferably arranged in two levels, such as the upper level nozzles <b>82</b> and the lower level nozzles <b>84</b>. The nozzles are positioned at suitable locations to allow solvent washing of the processing vessel interior surfaces. In the preferred construction there are two upper nozzles which are advantageously positioned at an angular spacing of 90°, at positions 0° and 90° . The two lower nozzles <b>84</b> are at 180° and 270° positions such that the nozzles are equiangularly spaced about the centerline. The position of nozzle <b>84</b> has been shifted in FIG. 3 for purposes of illustration. The chamber cleaning nozzles advantageously each have two nozzle openings to provide two jets which provide enhanced jet dispersion and greater spray washing effectiveness.

FIG. 3 also shows bowl <b>51</b> includes a frustoconical bottom bowl piece <b>53</b> which essentially defines the bottom wall of the processing vessel. The bottom wall also includes a drain having a drain fitting <b>60</b> and drain opening <b>61</b>. The bottom wail of the spray processing vessel also includes a spray assembly opening <b>62</b>. Spray assembly opening <b>62</b> receives portions of a spray assembly <b>70</b> therethrough. Spray assembly opening <b>62</b> is advantageously provided with a reinforcing boss <b>87</b> which defines the opening and is securely affixed to the bottom wall <b>53</b>, such as by welding. Spray assembly <b>70</b> produces a coating spray jet <b>69</b> of coating material and carrier gas which is directed onto the downwardly oriented face of wafer <b>50</b>.

FIG. 3 also shows a processing bowl side compartment <b>78</b> which extends partially along one exterior side of the processing bowl <b>51</b>. Side compartment <b>78</b> serves as a storage and nozzle cleaning compartment adjacent to the processing chamber <b>63</b>. Compartment <b>78</b> connects with processing chamber <b>63</b> via a storage compartment connection opening <b>88</b>. A spray arm wash-down nozzle <b>79</b> is mounted near the top of the storage compartment. When a spraying operation or series of operations have been completed, the spray arm is pivoted into the storage compartment <b>78</b>. The wash-down nozzle <b>79</b> is supplied with solvent to form a wash-down jet <b>109</b> which sprays solvent upon the spray-head <b>71</b> to, in particular, wash the coating spray nozzle <b>77</b>. This prevents buildup of coating material at the nozzle <b>77</b> which may otherwise cause pluggage or adversely affect the coating application jet <b>69</b>.

Spray Coating Station—Sprayer Assembly

FIG. 3 shows the sprayer assembly in sectional view to indicate the preferred construction. Sprayer <b>70</b> includes a spray-head <b>71</b> which is movable within the processing chamber <b>63</b> to effect motion of coating spray nozzle <b>77</b>. In the preferred construction shown, the spray-head <b>71</b> swings about a pivot axis <b>105</b>. This in combination with rotational movement of the wafer <b>50</b> allows all areas of the downwardly facing surface of wafer <b>50</b> to be coated.

The elevational position of the spray head <b>71</b> is preferably adjustable. FIG. 3 shows spray-head <b>71</b> in the axially downward position. In this downward or removed position the spray-head is spaced relatively further from the wafer. A phantom line box illustrates spray-head <b>71</b> in an alternative upward or close position when it has been moved upwardly into closer proximity to the wafer <b>50</b>. The elevational or proximity position of the spray head relative to the surface being coated is adjustable within a range of differing proximity positions lying between a closest position and a remotest position. This allows the operator to optimize coating performance according to the requirements associated with a particular coating being used and other associated coating application parameters. As shown, the adjustment is accomplished using a manual adjustment mechanism which is described below.

Spray-head <b>71</b> is mounted upon a spray-head shaft <b>86</b>. Spray-head shaft <b>86</b> forms part of a spray head actuator <b>85</b>. Spray-head actuator <b>85</b> includes an outer support tube <b>90</b> which mounted upon the reinforcing boss <b>87</b>, such as by threadably receiving the tube within the boss. A seal <b>89</b> is advantageously included near the upper end to seal between the boss and support tube. A pivot motor <b>91</b> is mounted upon the lower end of support tube <b>90</b>, preferably using a motor mounting flange <b>107</b> which is connected to the support tube, such as by welding. The pivot motor is fastened to flange <b>107</b> by fasteners (not shown).

Pivot motor <b>91</b> has an output shaft <b>92</b> which is connected by a coupling <b>93</b> to a pivot tube assembly <b>94</b>. The pivot tube assembly also advantageously includes an angular position indicator arm <b>104</b> which is detected by a pivot position sensor <b>119</b> (FIG. 11) to indicate the pivot position for control of the pivot arm movement. Angular position indicator arm <b>104</b> is connected to a connection piece <b>103</b>. Connection piece <b>103</b> is partially received in the upper end of the motor coupling <b>93</b>. Connection piece <b>103</b> is preferably connected to the an outer pivot tube <b>95</b>.

The pivot tube assembly includes outer pivot tube <b>95</b>. Outer pivot tube <b>95</b> pivots within support tube <b>90</b>. Outer pivot tube <b>95</b> is advantageously supported by bearings, such as the two bushing-type bearings <b>96</b>. An annular spacer <b>97</b> extends between and spaces bushings <b>96</b>. An outer seal <b>98</b> seals between pivot tube <b>95</b> and the inner diameter of support tube <b>90</b>. An inner seal <b>99</b> seals between the spray-head support shaft <b>86</b> and the inner diameter of pivot tube <b>86</b>.

Tubes <b>95</b> and shaft <b>86</b> pivot together in response to torque applied by the output shaft <b>92</b> of motor <b>91</b>. The elevational position of shaft <b>86</b> is adjustable relative to outer pivot tube <b>95</b>. Adjustment is accomplished by loosening a set screw <b>111</b> which is threadably received in a hole in outer pivot tube <b>95</b>. Shaft <b>86</b> is then moved to the desired elevation or proximity position and secured by tightening set screw <b>111</b>.

Pivot shaft <b>86</b> is made tubular to form a conduit passageway <b>112</b> therethrough. The conduit passageway allows a coating conduit <b>113</b> and carrier gas conduit <b>114</b> to extend from the spray head nozzle block <b>120</b> down passageway <b>112</b> for connection to related equipment described below. Conduits <b>113</b> and <b>114</b> extend through a lower conduit feed opening <b>115</b>. The angular position of the spray assembly is detected by an angular position sensor <b>119</b> (FIG. 11) which optically or otherwise senses the position of arm <b>104</b>.

Spray-head <b>71</b> includes a first spray arm part <b>101</b> which is secured to the upper end of pivot shaft <b>86</b>. A second spray arm part <b>102</b> is connected to first part <b>101</b> to form a tubular arm which extends outward from shaft <b>86</b>. Shaft <b>86</b> and spray arm <b>71</b> pivots about pivot axis <b>105</b>.

Spray-head <b>71</b> also includes a nozzle assembly mounting head <b>118</b> which is detachably connected to the distal end of second arm part <b>102</b> using fasteners (not shown). The nozzle head <b>118</b> mounts a nozzle block assembly <b>120</b>. Nozzle block <b>120</b> has a nozzle extension <b>121</b> which fits within a mounting aperture <b>122</b> formed in mounting head <b>118</b>. Nozzle extension <b>121</b> contains the nozzle <b>77</b> through which coating and any carrier gas are emitted. Nozzle block <b>120</b> is provided with fittings <b>123</b> and <b>124</b> which connect with the coating and carrier gas conduits <b>113</b> and <b>114</b>.

Nozzle block <b>120</b> is preferably a nozzle which provides good atomization of the coating liquid using a carrier gas. The preferred nozzle block has internal features which cause ultrasonic vibrations to be generated as the carrier gas passes through the nozzle block. The ultrasonic vibrations assist in providing good atomization of the coating with particle sizes in the range of 0.1-10 microns, more preferably on the order of approximately 1 micron in diameter. A suitable nozzle type is Sonicair brand atomizing nozzle available from Ivek Corp. of North Springfield, Vt.

Nozzle block <b>120</b> is preferably provided with nozzle block heaters <b>127</b> which are preferably electrical resistance heaters. The nozzle block heaters are preferably attached to both opposing sides of the nozzle block to heat the nozzle block and achieve an approximate desired temperature range. This serves in providing consistent viscosity control since the nozzle will be heated to an elevated temperature which stays approximately the same during operation. Suitable temperatures are in the approximate range of 20-150° C., more preferably 30-100° C., even more preferably 40-80° C. Temperature can be controlled by varying the current passing through the nozzle block heaters.

FIG. 9 shows an alternative form of spray assembly according to the invention. In this view the spray arm head piece <b>118</b> has been substituted by an alternative three nozzle head piece <b>218</b>. Head piece <b>218</b> mounts three nozzle blocks similar to nozzle block <b>120</b>. Each nozzle block has an emitting nozzle <b>77</b> and associated heaters. This arrangement provides a more diffuse spray pattern. Otherwise the construction is similar with minor modifications associated with the increased number of nozzles.

Spray Coating Station—Sprayer Fluid Supply

FIG. 10 shows a preferred system for supplying coating fluid and carrier gas to the nozzle block <b>120</b>. Air, nitrogen or other suitable carrier gas is supplied from a facilities source via a cutoff valve <b>220</b>. The gas then goes through a gas heater <b>221</b>. A thermostatic control sensor <b>222</b> measures the temperature of the downstream gas passing through heater <b>221</b>. Heater <b>221</b> is thus controlled to achieve a desired gas temperature. Alternatively sensor <b>222</b> can supply a signal to the central controller <b>300</b> (FIG. 11) and gas heater <b>221</b> can be used to controllably heat the carrier gas to a desired temperature. A pressure regulator <b>223</b> is downstream from heater <b>221</b> and is used to regulate the pressure of carrier gas being fed to nozzle block <b>120</b>.

FIG. 10 also shows a coating fluid supply system. Coating is held in a coating reservoir <b>230</b>. A control valve <b>231</b> can be included between the reservoir and pump <b>233</b>. Pump <b>233</b> is preferably a precision controlled metering pump used with the preferred Sonicair brand nozzle described above and available from the same indicated source. The pump is controlled using a matching pump controller <b>235</b> which controls the pump and its related electrical operating motor to provide the desired flow rate. Coating is supplied to the nozzle block <b>120</b> via coating conduit <b>113</b>. Typical operating pressures are in the range of 5-100 pounds per square inch gauge pressure (psi), more preferably 10-30 psi.

Spray Coating Station—Processing Head

FIG. 4 shows The preferred construction for processing head <b>49</b>. Head <b>49</b> is constructed similar to wafer processing head(s) shown and described in U.S. Pat. No. 5,235,995, issued Aug. 17, 1993 which is hereby incorporated by reference. Also pertinent are alternative processor head constructions shown and described in U.S. Pat. No. 5,431,421, issued Jul. 11, 1995, which is hereby incorporated by reference. For purposes of convenience and facilitating the understanding of this invention without specific reference to such earlier patent, additional description is set out herein.

It should also be noted as a preliminary matter that the cutting plane used in FIG. 4 changes orientation at the centerline of the rotor to better illustrate additional features of the invention.

Processing head <b>49</b> includes a shroud <b>313</b> which forms a main structural part of the head and is connected shaft <b>80</b>. Shaft <b>80</b> is mounted to shroud <b>313</b> using mounting rings <b>132</b> and fasteners (not shown). Shaft <b>80</b> is pivotable by a head operator <b>131</b> (see FIG. <b>2</b>). Head operator <b>131</b> lifts shaft <b>80</b> and attached head <b>49</b> up and down. Operator <b>131</b> also pivots shaft <b>80</b>. Pivoting shaft <b>80</b> causes the attached head <b>49</b> to flip between face-up and face-down positions.

Shroud <b>313</b> is generally disk-shaped. The outer edge of shroud <b>313</b> forms a rim <b>318</b>. The face of shroud <b>313</b> has annular recesses <b>319</b> which receive portions of a wafer support piece <b>330</b> in proximity thereto. Wafer support piece <b>330</b> is mounted for rotation relative to shroud <b>313</b>. Shroud <b>313</b> is also provided with a central opening through which portions of a motor support <b>358</b> are received.

Head <b>49</b> also has a housing <b>329</b> attached to shroud <b>313</b> in which the motor and other parts are enclosed. A top cap <b>360</b> is connected to the housing to further enclose the internal mechanical workings of head <b>49</b>. The shroud, housing and cap are advantageously made of polyvinylidene fluoride or other suitable materials.

The processor head includes spacers or columns <b>326</b> which extend from lower motor mount <b>358</b> upwardly to support the upper mount <b>327</b>. Spacers <b>326</b> have interior bores which receive fasteners (not shown) which extend through apertures formed through mount <b>327</b>.

Processor head <b>49</b> also includes a wafer holder or support <b>330</b>. Wafer support <b>330</b> is movably mounted to remaining parts of the head assembly to provide rotation or other appropriate relative motion between the wafer being processed and the spray assembly <b>71</b>. The wafer support includes a disk-shaped wafer support plate <b>339</b> having an exposed downwardly directed front face and an upwardly directed back face removed from the wafer <b>50</b> being processed. The wafer support plate <b>339</b> is advantageously constructed of polypropylene or other suitable material with an upturned flange <b>362</b> about the periphery thereof. Flange <b>362</b> can advantageously be provided with upwardly facing parallel extensions and associated grooves <b>363</b> to help restrict gas flow between flange <b>362</b> and shroud <b>319</b>.

The wafer support <b>330</b> also includes a wafer support reinforcing wheel <b>390</b> which is secured within the wafer support piece <b>339</b> using a mounting ring <b>391</b>. The reinforcing wheel <b>390</b> has a hub <b>392</b> to which is connected the output of motor <b>359</b>. Such connection is described more fully below.

Wafer support <b>330</b> mounts a plurality of wafer support fingers <b>334</b>, such as the four shown, or more. The wafer support fingers <b>334</b> have distal ends <b>337</b> which are formed to provide gripping notches <b>338</b> in which the peripheral edge of wafer <b>50</b> is held. The distal ends of support fingers <b>334</b> are spatially contracted toward one another to hold wafer <b>50</b>, or expanded outwardly to release the wafer.

FIG. 4 shows that wafer support fingers <b>334</b> are flexibly mounted by finger bushings <b>335</b> to allow deflection thereof and the relative expansion and contraction needed for controlled gripping and release of wafer <b>50</b>. Finger bushings <b>335</b> are preferably integrally formed with fingers <b>334</b>. The finger bushings have an enlarged diameter exposed surface flange <b>321</b> which faces downwardly toward wafer <b>50</b>. The finger bushings are held in position by a retaining ring <b>322</b> mounted to engage the back or upper surface of wafer support plate <b>339</b>. The exposed, lower face also in part defines an annular web or diaphragm <b>323</b> which provides the flexibility needed to allow fingers <b>334</b> to pivotally deflect between expanded and contracted positions. The finger bushings <b>335</b> are made of a flexible material, such as TEFLON or other material suitable for service in the chemical environment which exists within processing chamber <b>63</b>

The wafer support fingers <b>334</b> also have upper or proximate ends which are provided with connection receptacles <b>325</b>. The connection receptacles receive end pieces <b>342</b> therein to form a mechanical coupling. End pieces <b>342</b> are displaced laterally by finger connection rods <b>344</b> to tilt the end pieces and attached wafer support fingers. The tilting action causes the relative expansion and contraction of the distal ends of the support fingers in the triad arrangement.

Actuation of the support fingers is advantageously accomplished using finger actuators <b>343</b>. The finger actuators <b>343</b> each include a connecting rod <b>344</b> which is pivotally connected at a first or outer end to an end piece <b>342</b>. The inner or second ends of connecting rods <b>344</b> are pivotally connected to a remote end of a positioning link <b>345</b>. The opposite or mounted ends of positioning links <b>345</b> are pivotally connected to the wafer support plate <b>339</b> using positioning link brackets <b>347</b>. The positioning links <b>345</b> are oriented at oblique angles extending inwardly from the pivotal connections with the brackets <b>347</b> toward the remote ends and the pivotal connections with connecting rods <b>344</b>. The positioning links <b>345</b> can be provided with biasing springs <b>387</b> which urge links <b>345</b> upwardly and the associated wafer fingers <b>334</b> into contracted positions tending to grip the wafer.

The wafer support fingers are moved into expanded positions to release the wafer by displacing the pivotal joints between connecting rods <b>344</b> and positioning links <b>345</b> downwardly and inwardly. This causes the connecting rods to move inwardly in a radial direction to displace the proximate ends of the wafer fingers inwardly and the opposite distal ends outwardly to release the wafer. The connecting rods are displaced downwardly and inwardly by an annular contact ring <b>351</b>. Contact ring <b>351</b> is operated by a pair of small pneumatic pistons <b>349</b>. Pistons <b>349</b> are slidable within cylindrical piston cylinders <b>350</b> formed in motor support <b>358</b>. Pressurized fluid is supplied to the upper sides of pistons <b>349</b> to force them downwardly and cause contact between annular contact ring <b>351</b> and connecting rods <b>344</b>.

The wafer support piece <b>339</b> is also advantageously provided with a set of four standoffs <b>382</b> which serve to support wafer <b>50</b> during loading of the processing head. Wafer <b>50</b> is loaded with the head in a face-up position with the distal end of the standoffs available to be contacted by the backside of wafer <b>50</b>.

The wafer support drive assembly includes a motor <b>359</b> which is mounted upon motor support <b>358</b>. Motor <b>359</b> is preferably a brushless DC motor. Motor <b>359</b> has a hollow motor shaft <b>353</b> supported by a set of ball bearings <b>355</b>. The hollow motor shaft <b>353</b> receives a detachable shaft <b>354</b> therethrough. Detachable shaft <b>354</b> is threadably connected to a shaft head <b>383</b>. Shaft head <b>383</b> includes an enlarged flange <b>356</b>. The shaft head is connected to the motor shaft to rotate therewith using a pin (not shown) or other suitable means. The flanged head is received within a shaft head receptacle <b>368</b> formed in the back surface of hub <b>392</b>. Spaced, axially oriented, anti-rotation pins <b>357</b> are engaged between the lower face of the flanged shaft head <b>356</b> and corresponding holes formed in receptacle <b>368</b>. A snap-ring retainer <b>369</b> holds the flanged head <b>356</b> axially within receptacle <b>368</b>.

The angular positions of fingers <b>334</b> about the rotating assembly rotational axis X—X are preferably controlled to assume desired positions when the rotatable wafer support <b>330</b> stops. This indexing of the stationary positions of fingers <b>334</b> is needed when the processing head is opened to provide proper engagement of the wafer by the robotic transfer unit engagement head.

A preferred indexing means <b>250</b> used to position the wafer support, motor and other rotatable parts forming the rotating assembly of the processing head drive. Rotor positioning or indexing mechanism <b>250</b> includes a multi-sided cammed rotor plate <b>259</b> mounted to rotate with motor shaft <b>353</b> using coupling <b>271</b>. The cam plate <b>259</b> has a plurality of sides equal in number to the number of fingers <b>334</b>. Each side of rotor plate <b>259</b> has a curved edge configuration. The curved configurations of each of the three side segments are sloped relative to a circle defined by axis X—X. The curves slope from high points at the adjoining ends of the side segments toward central low points. The central low points serve as a detent when engaged by an edge engagement roller (not shown) which is controllably forced inward. When motor <b>359</b> is inoperative and the motor shaft is freely rotatable, the inward force of the roller causes rotor plate <b>259</b> to pivot to bring the rotating assembly into an angular position which centers the roller within a low point of the cammed rotor plate.

A motion monitoring assembly is also advantageously provided within processing head <b>49</b> for measuring the speed and direction of rotation of the wafer plate <b>330</b> about the rotational axis X—X. The motion monitoring assembly includes a rotor indicating element, such as rotor indicator disk <b>254</b>. Indicator disk <b>254</b> is provided with a series of peripheral notches which intermittently pass and interrupt one or more optical beams and associated sensors (not shown).

Wafer Thermal Treatment Station

FIGS. 6-8 show a preferred form of thermal treatment station <b>46</b>. Thermal treatment station <b>46</b> includes three bays or receiving chambers <b>221</b>-<b>3</b>. Receiving bays <b>221</b>-<b>3</b> are designed to each receive a single wafer which has been coated in the spray coating station <b>40</b>. The top and bottom receiving bays <b>221</b>-<b>2</b> are associated with thermal treatment units in the form of wafer heaters <b>225</b>. The middle receiving bay <b>223</b> is provided with a thermal treatment unit in the form of a wafer cooler. The wafer heaters and cooler are constructed similarly. The preferred construction of both will now be described with specific reference to a wafer heater <b>225</b>. The difference between the heaters and cooler will be noted in the description.

FIG. 8 shows a preferred wafer heater <b>225</b>. A wafer <b>50</b> is positioned upon the upper surface of a platen <b>226</b>. Platen <b>226</b> is preferably constructed with features that improve heat transfer between wafer <b>50</b> and the platen. More Specifically, the upper or contact surface <b>227</b> of the platen is formed to fit against the back surface of wafer <b>50</b>. As shown, wafer <b>50</b> and the contact surface <b>227</b> have flat complementary contacting surfaces. The platen is preferably made from a metal of good thermal conductivity, such as aluminum. The contact surface of the platen is also preferably provided with a network or array of vacuum aperture grooves <b>228</b>. As shown, vacuum apertures <b>228</b> are constructed as three concentric grooves which are controllably connected to a vacuum supply and supplied with vacuum pressure when the wafer is to be held in position upon platen <b>226</b>. The vacuum pressure applied over the back side of wafer <b>50</b> pulls the wafer into better contact with the platen thus improving heat transfer. Vacuum is supplied to grooves <b>228</b> via vacuum conduits (not shown) formed in the platen.

The wafer heater is also preferably provided with a thermal source element <b>230</b> which is mounted to contact the back surface of platen <b>226</b>. In the wafer heater <b>225</b> the thermal source element <b>230</b> is a serpentine electrical resistance heater. In the wafer cooler used for bay <b>223</b>, the thermal source element is an array of cooling passages (not shown) through which are circulated a cooling fluid. Alternatively, a thermoelectric cooler or other suitable cooling apparatus formed in the shape of a relatively thin layer.

Thermal treatment unit <b>225</b> also has an insulatory back piece <b>231</b> which extends over the back of the platen and interposed heater or cooler <b>230</b>. Insulation piece <b>231</b> is preferably formed of a suitable ceramic material having relatively good thermal insulating properties. A variety of suitable materials are available.

The platen <b>226</b>, thermal source element <b>230</b>, and insulating piece <b>231</b> are backed with a support plate <b>232</b>. A fastener <b>234</b> is advantageously used to assembly these pieces. Fastener <b>234</b> is provided with male threads along it length and is received within mounting apertures formed in all four of the pieces. The mounting aperture in platen <b>226</b> is threaded. A spacer <b>235</b> is positioned adjacent the back support plate <b>232</b> and serves to space between plate <b>235</b> and a radiant shield plate <b>236</b> which reduces radiant heat transfer. The lower end of fastener <b>234</b> is received in a standoff <b>237</b> having internal female threads. The lower end of standoff <b>237</b> is fastened to the unit frame piece <b>238</b> using fastener <b>239</b>. Thermal unit <b>235</b> preferably uses four assembly mountings as just described.

Thermal treatment unit <b>225</b> also has a lifting mechanism <b>240</b> for lifting wafer <b>50</b> from the surface of the platen. Lifting mechanism <b>240</b> includes a lifting actuator. The lifting actuator preferably includes a stepper motor <b>241</b> which has an output shaft which mounts a circular or other suitable cam <b>242</b>. Cam <b>242</b> is eccentric upon the output shaft to controllably raise and lower a cam follower <b>271</b>. Cam follower <b>271</b> is advantageously a rotatable bearing with associated outer race which contacts cam <b>271</b>. Cam follower <b>271</b> is connected to an actuator plate <b>243</b> which moves up and down with controlled angular movement of the motor <b>241</b>. Three lifting rod assemblies <b>245</b> are held in the platen assembly in a tripod arrangement. The lifting rod assemblies are contacted by the actuator plate and are moved upwardly and downwardly in response to operation of actuator <b>241</b>.

Lifting rod assemblies <b>245</b> include a contact rod <b>246</b>. Contact rod <b>246</b> is provided with an enlarged head <b>247</b> which is mounted for linear travel in a lifting rod receiving pocket <b>248</b>. The contact rod also connects with a connector <b>249</b> which is slidably received through apertures formed through the back piece <b>232</b> and heat shield <b>236</b>. A lift biasing spring <b>252</b> is compressed between the underside of shield <b>236</b> and a connector contact head <b>251</b>. Spring <b>252</b> biases the contact rod upwardly to lift wafer <b>50</b>. Actuator <b>240</b> overpowers the biasing springs to retract the contact rods downwardly. The rods can be fully or partially retracted to achieve contact or a desired proximity of the wafer to the platen <b>227</b>.

Control System

FIG. 11 shows a schematic presentation of the preferred control system. In such there is a central controller <b>300</b> which is connected to various control system components which are either activated or provide sensory input information. Many alternative control system configurations are possible. As shown, the wafer transfer <b>41</b>, touch screen display <b>31</b>, disk drive <b>32</b>, stop switch <b>33</b>, keyboard port <b>34</b>, spray arm motor <b>91</b>, pump controller <b>235</b>, thermal treatment station operator <b>221</b>, processing head <b>49</b>, head operator <b>131</b>, thermal treatment station lift <b>240</b>, and spray pivot sensor <b>119</b> are shown connected to the central controller.

Methods and Operation

The invention further includes novel methods for processing microelectronic or semiconductor articles to provide a coating thereon. The preferred methods are directed to, processing methods which can provide a coating which conforms to surface irregularities which are necessarily a part of chemically etched or otherwise irregularly formed surface topologies.

In one form of the invention, the novel methods preferably include loading one or more wafers or other semiconductor articles into a processing enclosure. This is advantageously accomplished by opening the access door <b>24</b> and loading an input wafer cassette <b>57</b> into the input station position <b>43</b>. The methods further advantageously include closing the access door and thereby substantially enclosing the processing compartment <b>15</b>

The preferred methods also advantageously can include transferring a wafer from the input station. This transferring is accomplished by inserting a wafer engagement tool, such as tool <b>67</b>, into juxtaposition with wafer <b>50</b> and applying a vacuum force to effect holding of the wafer upon the engagement tool. The transferring also preferably includes moving the wafer from the input station by moving the wafer transfer apparatus <b>41</b>.

The novel methods also preferably include positioning a wafer or other article within a spray processing vessel. This is done in the processing system <b>10</b> by loading the semiconductor article being coated into the spray coating station <b>40</b> and closing the processing vessel parts. Loading is preferably effected by lifting or raising the processing head <b>49</b>. Loading further advantageously includes pivoting the wafer holding processing head into a face-up position to receive the wafer thereon. Loading also can include expanding the wafer engagement fingers into open positions to receive the wafer <b>50</b> therebetween, and then closing the fingers into engaging positions which hold the wafer. The loading phase further preferably includes pivoting processing head <b>49</b> into a face-down position adjacent to the processing vessel bowl <b>51</b>. The processing vessel is then effectively closed by lowering or otherwise bringing the processing head into complementary relationship with the vessel bowl. Assembling the processing head and bowl together in conjoined relationship produces a substantially enclosed processing chamber <b>63</b> in which the wafer is coated.

In preferred forms of the invention the novel methods further may include rotating or otherwise moving the wafer. This is accomplished in processor <b>10</b> by rotating the processing head motor and attached wafer support piece <b>136</b>. The rotating step is preferably accomplished at rotational speeds in the range of 1-1000 revolutions per minute, more preferably 10-300 revolutions per minute, even more preferably 50-200 revolutions per minute.

The methods further include spraying the wafer or other semiconductor or microelectronic article which has been positioned within the processing vessel. Spraying is accomplished while moving the spray head assembly <b>71</b>. The moving of the spray head causes the nozzle or nozzles <b>77</b> to move relative to the article being coated. The spray head assembly is preferably pivoted to cause the relative movement between the nozzle <b>77</b> and the wafer surface. The rotational speed and relative movement of the nozzles are coordinated to achieve a uniform conformal layer of coating material.

In preferred methods according to this invention, the spray arm is advantageously started in a radial position outboard of the piece being coated. The spray can be started from the nozzle in an outboard position to reduce or eliminate any transitory startup effects before the coating spray contacts the wafer surface. Thereafter the spray arm is pivoted so that nozzle or nozzles <b>77</b> are swept to or through the rotational axis of the wafer. This movement of the spray nozzles is coordinated so that the coating application rate density is uniform over the area being coated. In the preferred methods the radial velocity of the nozzles relative to the wafer rotational centerline is increased as the nozzle position moves toward the center of rotation. Conversely, as the nozzle moves outwardly during any return spraying process, the radial velocity decreases. The nozzle path velocity is ideally a function which is inversely proportional to the radial position of the nozzle relative to the rotational centerline of the wafer. Even more preferably, the nozzle path velocity is a function which is inversely proportional to the square of the radial position of the nozzle.

The coordinated application step also considers the application rate which is precisely controlled to effect metering of the spray coating liquid. This metering is performed in system <b>10</b> by the coordinated operation of spray pump <b>233</b>, pump controller <b>235</b>, and associated carrier gas flow rate. In the coating of semiconductor wafers, liquid coating pump rates in the approximate range of 1-1000 microliters per second are potentially useful, more preferably 5-300 microliters per second, even more preferably 10-100 microliters per second. The coating flow rate to the nozzles is most preferably kept at a constant or nearly constant rate during the spraying operation. This has been found advantageous in providing stable operation.

The methods according to this invention also preferably use carrier gas flows which provide significant coating particle velocities. Increased coating particle velocities aid in impacting the particles against the surface of the wafer or other article being coated to provide better conformal coating application.

It may be preferable in some coating applications to utilize carrier gases which participate in or are specifically inert to the chemistry involved. For example, in the application of polyimide coatings it has been found desirable to utilize nitrogen instead of air. The processing chamber is preferably purged with nitrogen and the carrier gas used is also nitrogen. This reduces chemical effects upon the polyimide which are associated with moisture which is present in air supplies even when treated to reduce or remove moisture. In other situations the carrier gases used may enhance or retard coating setup rates and may be desirable with the particular coating being applied.

In some forms of the invention, novel methods include heating the carrier gas which is used in the spraying. This heating is effected in the preferred embodiment using heater <b>221</b>. The spraying also preferably includes regulating the carrier gas pressure. Pressures in the range of approximately 0-25 pounds per square inch gauge are believed appropriate, more preferably carrier gas pressures are regulated to be in the approximate range of 5-15 pounds per square inch gauge. The volume of carrier gas can vary from none to relatively high flow rates depending upon the coating being applied. The figures given above are for nozzles having an approximate orifice diameter in the range ⅛-{fraction (1/16)} inch.

The spraying also preferably includes generating a sonic vibratory resonance within the spray block to cause atomizing to be performed to achieve the approximate coating particle sizes indicated above. The generating of vibratory resonance is preferably effected by passing the carrier gas through a suitable nozzle structure, such as the ultrasonic nozzle explained above.

Spraying according to the novel methods of this invention also advantageously includes controlling the viscosity of the coating liquid being applied. This controlling is advantageously effected by heating the coating to achieve greater stability with regard to viscosity fluctuations. The heating is best done by heating the nozzle block <b>120</b> using the heaters <b>127</b>. The controlled heating of the carrier gas is also a relevant parameter in achieving control of the coating viscosity.

The preferred methods may also advantageously include providing a purge of gas along the back side of wafer <b>50</b>. This purging of the atmosphere along the wafer back side helps to prevent coating overspray from settling and adhering to the back side of the wafer. Such a purging function is accomplished with a gas purge port (not shown) which supplies purge gas to the back side of support piece <b>339</b> and an aperture which is formed through support piece <b>339</b> at a desired location.

The methods of this invention further include removing or unloading the coated wafer or other semiconductor article from the processing chamber. This is advantageously accomplished by opening the processing vessel. Opening the processing vessel includes lifting or otherwise removing the processing head <b>49</b> from the processing bowl <b>51</b>. It further preferably includes pivoting the processing head to turn the wafer into a coated-side-up or face-up position.

Unloading also preferably includes engaging the wafer with the wafer engagement tool in the same or very similar manner described above with regard to transferring the wafer from the input station.

The coated wafer is then preferably transferred to a thermal treatment station, such as thermal treatment station <b>46</b>. This is done using the wafer transfer <b>41</b>. The process of transferring the wafer also includes loading or installing the wafer into a thermal treatment receiver, such as either of the heating treatment chambers <b>221</b> or <b>222</b>. During loading of the thermal treatment chambers, the wafer contact members <b>246</b> are extended. Thus the extending step should be performed before installing the wafer into the thermal treatment chamber. The wafer transfer functions by gently lowering the wafer onto the contact members. Thereafter the engagement tool functions by retracting from the thermal treatment chamber. The thermal treatment unit then functions by lowering the lifting mechanism <b>240</b>. The lowering or moving into proximity can result in a desired proximity spacing, such as 0.5-1 millimeter. In other coating applications it may be preferred to perform the positioning by contacting the wafer against the platen <b>226</b> by fully retracting the contact members <b>246</b>. The wafer is then subjected to vacuum by applying vacuum pressures via channels <b>228</b> which causes a forcing of the wafer against the platen.

The methods further preferably include transferring heat relative to the wafer. In the most preferred methods the heat transferring includes both heating and cooling. The heating step is preferably accomplished first. The heating is effected by activating the heater <b>225</b> to heat the platen and allow heat to flow from the platen to the wafer. The heating is preferably performed for sufficient time to render the coating mechanically stable upon the surface of the wafer. The time needed to accomplish this will vary depending on the coating and wafer being coated. In many situations, the heat treatment time will be in the range of 1-10 minutes, more preferably 1-3 minutes. Thereafter the vacuum pressure is reduced thereby releasing the force applied by the vacuum. The wafer is then readied for removal by lifting or otherwise extending the wafer using the wafer lifting mechanism.

After the heating step, the wafer is then most preferably transferred from a heating chamber <b>221</b> or <b>222</b>, to the cooling chamber <b>223</b>. The loading process is the same or similar to that described above in connection with the heating chamber. The cooling treatment process is also very similar to that described above for the heating process. The cooling treatment in general requires about one-half the time required for the heat treatment curing of the coating. Thus the need for only one cooling unit for two heating units.

After the coated wafer has been coated, and then heated, cooled or both, it is again transferred by wafer transfer <b>41</b>. The wafer transfer moves the wafer to the output station <b>44</b>. At the output station, the wafer transfer performs by inserting the wafer into the output station carrier <b>58</b> in an available space therein. When all wafers of a batch have been completed, the output wafers are removed by opening the access door and manually removing the carrier.

In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.

<tables><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217pt" align="center" /><thead><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Listing of Subtitles &amp; Reference Numerals</entry></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="offset" colwidth="49pt" align="left" /><colspec colname="1" colwidth="168pt" align="left" /><tbody valign="top"><row><entry /><entry>System Generally</entry></row><row><entry /><entry>Processing system 10</entry></row><row><entry /><entry>frame or framework 11</entry></row><row><entry /><entry>rollable casters 14</entry></row><row><entry /><entry>control side or section 12</entry></row><row><entry /><entry>wafer processing side or section 13</entry></row><row><entry /><entry>processing compartment 15</entry></row><row><entry /><entry>equipment storage compartment 16</entry></row><row><entry /><entry>front 18</entry></row><row><entry /><entry>access panels 28</entry></row><row><entry /><entry>catches 29</entry></row><row><entry /><entry>sides 20 and 22</entry></row><row><entry /><entry>back 21</entry></row><row><entry /><entry>top 19</entry></row><row><entry /><entry>access door 24</entry></row><row><entry /><entry>using hinges 26</entry></row><row><entry /><entry>view window 25</entry></row><row><entry /><entry>control subsystem 30</entry></row><row><entry /><entry>display 31</entry></row><row><entry /><entry>data disk drive 32</entry></row><row><entry /><entry>keyboard connection port 34</entry></row><row><entry /><entry>emergency stop button 33</entry></row><row><entry /><entry>control system computer 300</entry></row><row><entry /><entry>top cover 27</entry></row><row><entry /><entry>exhaust port 48</entry></row><row><entry /><entry>Wafer Transfer</entry></row><row><entry /><entry>processing compartment deck 23</entry></row><row><entry /><entry>robotic wafer transfer station 41</entry></row><row><entry /><entry>first arm 65</entry></row><row><entry /><entry>base 64</entry></row><row><entry /><entry>extension cylinder 42</entry></row><row><entry /><entry>second arm 66</entry></row><row><entry /><entry>wafer engagement tool 67</entry></row><row><entry /><entry>Wafer Input and Output Stations</entry></row><row><entry /><entry>wafer input station 43</entry></row><row><entry /><entry>wafer output station 44</entry></row><row><entry /><entry>input wafer carrier 57</entry></row><row><entry /><entry>output wafer carrier 58</entry></row><row><entry /><entry>Introduction to Process</entry></row><row><entry /><entry>Spray Coating Station</entry></row><row><entry /><entry>spray coating station 40</entry></row><row><entry /><entry>processing head assembly 49</entry></row><row><entry /><entry>wafer 50</entry></row><row><entry /><entry>spray processing vessel bowl 51</entry></row><row><entry /><entry>spray processing vessel 56</entry></row><row><entry /><entry>processing chamber 63</entry></row><row><entry /><entry>processing bowl top opening 59</entry></row><row><entry /><entry>processing head shaft 80</entry></row><row><entry /><entry>processing head operator 131</entry></row><row><entry /><entry>Spray Coating Station - Processing Vessel</entry></row><row><entry /><entry>Bowl</entry></row><row><entry /><entry>processing vessel bowl portion 51</entry></row><row><entry /><entry>sidewall 52 </entry></row><row><entry /><entry>top opening flange 54</entry></row><row><entry /><entry>seal groove 55</entry></row><row><entry /><entry>upper level nozzles 82</entry></row><row><entry /><entry>lower level nozzles 84</entry></row><row><entry /><entry>drain fitting 60</entry></row><row><entry /><entry>drain opening 61</entry></row><row><entry /><entry>spray assembly opening 62</entry></row><row><entry /><entry>reinforcing boss 87</entry></row><row><entry /><entry>bottom wall 53</entry></row><row><entry /><entry>coating spray jet 69</entry></row><row><entry /><entry>processing bowl side compartment 78</entry></row><row><entry /><entry>storage compartment connection</entry></row><row><entry /><entry>opening 88</entry></row><row><entry /><entry>spray arm wash-down nozzle 79</entry></row><row><entry /><entry>Spray Coating Station - Sprayer Assembly</entry></row><row><entry /><entry>spray-head 71</entry></row><row><entry /><entry>coating spray nozzle 77</entry></row><row><entry /><entry>pivot axis 105</entry></row><row><entry /><entry>spray-head shaft 86</entry></row><row><entry /><entry>spray head actuator 85</entry></row><row><entry /><entry>outer support tube 90</entry></row><row><entry /><entry>seal 89</entry></row><row><entry /><entry>pivot motor 91</entry></row><row><entry /><entry>motor mounting flange 107</entry></row><row><entry /><entry>output shaft 92</entry></row><row><entry /><entry>coupling 93</entry></row><row><entry /><entry>pivot tube assembly 94</entry></row><row><entry /><entry>angular position indicator arm 104</entry></row><row><entry /><entry>pivot position sensor 119</entry></row><row><entry /><entry>connection piece 103</entry></row><row><entry /><entry>outer pivot tube 95</entry></row><row><entry /><entry>bushing-type bearings 96</entry></row><row><entry /><entry>annular spacer 97</entry></row><row><entry /><entry>outer seal 98</entry></row><row><entry /><entry>inner seal 99</entry></row><row><entry /><entry>set screw 111</entry></row><row><entry /><entry>conduit passageway 112</entry></row><row><entry /><entry>coating conduit 113</entry></row><row><entry /><entry>carrier gas conduit 114</entry></row><row><entry /><entry>spray head nozzle block 120</entry></row><row><entry /><entry>first spray arm part 101</entry></row><row><entry /><entry>second spray arm part 102</entry></row><row><entry /><entry>nozzle assembly mounting head 118</entry></row><row><entry /><entry>nozzle extension 121</entry></row><row><entry /><entry>mounting aperture 122</entry></row><row><entry /><entry>nozzle block heaters 127</entry></row><row><entry /><entry>alternative three nozzle head piece 218</entry></row><row><entry /><entry>Spray Coating Station - Sprayer Fluid</entry></row><row><entry /><entry>Supply</entry></row><row><entry /><entry>cutoff valve 220</entry></row><row><entry /><entry>gas heater 221</entry></row><row><entry /><entry>thermostatic control sensor 222</entry></row><row><entry /><entry>central controller 300</entry></row><row><entry /><entry>pressure regulator 223</entry></row><row><entry /><entry>coating reservoir 230</entry></row><row><entry /><entry>control valve 231</entry></row><row><entry /><entry>pump 233</entry></row><row><entry /><entry>pump controller 235</entry></row><row><entry /><entry>Spray Coating Station - Processing Head</entry></row><row><entry /><entry>processing head 49</entry></row><row><entry /><entry>shroud 313</entry></row><row><entry /><entry>shaft 80</entry></row><row><entry /><entry>mounting rings 132</entry></row><row><entry /><entry>head operator 131</entry></row><row><entry /><entry>rim 318</entry></row><row><entry /><entry>annular recesses 319</entry></row><row><entry /><entry>wafer support piece 330</entry></row><row><entry /><entry>motor support 358</entry></row><row><entry /><entry>housing 329</entry></row><row><entry /><entry>top cap 360</entry></row><row><entry /><entry>spacers or columns 326</entry></row><row><entry /><entry>upper mount 327</entry></row><row><entry /><entry>Spacers 326</entry></row><row><entry /><entry>wafer holder or support 330</entry></row><row><entry /><entry>disk-shaped wafer support plate 339</entry></row><row><entry /><entry>upturned flange 362</entry></row><row><entry /><entry>parallel extensions and associated</entry></row><row><entry /><entry>grooves 363</entry></row><row><entry /><entry>wafer support reinforcing wheel 390</entry></row><row><entry /><entry>mounting ring 391</entry></row><row><entry /><entry>hub 392</entry></row><row><entry /><entry>wafer support fingers 334</entry></row><row><entry /><entry>distal ends 337</entry></row><row><entry /><entry>gripping notches 338</entry></row><row><entry /><entry>finger bushings 335</entry></row><row><entry /><entry>exposed surface flange 321</entry></row><row><entry /><entry>retaining ring 322</entry></row><row><entry /><entry>annular web or diaphragm 323</entry></row><row><entry /><entry>upper or proximate ends 341</entry></row><row><entry /><entry>connection receptacles 325</entry></row><row><entry /><entry>end pieces 342</entry></row><row><entry /><entry>finger connection rods 344</entry></row><row><entry /><entry>finger actuators 343</entry></row><row><entry /><entry>positioning link 345</entry></row><row><entry /><entry>positioning link brackets 347</entry></row><row><entry /><entry>biasing springs 387</entry></row><row><entry /><entry>annular contact ring 351</entry></row><row><entry /><entry>pneumatic pistons 349</entry></row><row><entry /><entry>piston cylinders 350</entry></row><row><entry /><entry>standoffs 382</entry></row><row><entry /><entry>motor 359</entry></row><row><entry /><entry>motor support 358</entry></row><row><entry /><entry>hollow motor shaft 353</entry></row><row><entry /><entry>ball bearings 355</entry></row><row><entry /><entry>detachable shaft 354</entry></row><row><entry /><entry>shaft head 383</entry></row><row><entry /><entry>flange 356</entry></row><row><entry /><entry>shaft head receptacle 368</entry></row><row><entry /><entry>hub 392</entry></row><row><entry /><entry>anti-rotation pins 357</entry></row><row><entry /><entry>snap-ring retainer 369</entry></row><row><entry /><entry>indexing means 250</entry></row><row><entry /><entry>cammed rotor plate 259</entry></row><row><entry /><entry>coupling 271</entry></row><row><entry /><entry>rotor indicator disk 254</entry></row><row><entry /><entry>Wafer Thermal Treatment Station</entry></row><row><entry /><entry>thermal treatment station 46</entry></row><row><entry /><entry>bays or receiving chambers 221-3</entry></row><row><entry /><entry>wafer heaters 225</entry></row><row><entry /><entry>middle receiving bay 223</entry></row><row><entry /><entry>wafer heater 225</entry></row><row><entry /><entry>platen 226</entry></row><row><entry /><entry>upper or contact surface 227</entry></row><row><entry /><entry>vacuum aperture grooves 228</entry></row><row><entry /><entry>thermal source element 230</entry></row><row><entry /><entry>insulatory back piece 231</entry></row><row><entry /><entry>support plate 232</entry></row><row><entry /><entry>fastener 234</entry></row><row><entry /><entry>spacer 235</entry></row><row><entry /><entry>radiant shield plate 236</entry></row><row><entry /><entry>she-bolt 237</entry></row><row><entry /><entry>unit frame piece 238</entry></row><row><entry /><entry>fastener 239</entry></row><row><entry /><entry>lifting mechanism 240</entry></row><row><entry /><entry>stepper motor 241</entry></row><row><entry /><entry>cam 242</entry></row><row><entry /><entry>cam follower 271</entry></row><row><entry /><entry>actuator plate 243 which moves up and</entry></row><row><entry /><entry>down with controlled angular</entry></row><row><entry /><entry>movement of the motor 241</entry></row><row><entry /><entry>lifting rod assemblies 245</entry></row><row><entry /><entry>contact rod 246</entry></row><row><entry /><entry>enlarged head 247</entry></row><row><entry /><entry>lifting rod receiving pocket 248</entry></row><row><entry /><entry>connector 249</entry></row><row><entry /><entry>lift biasing spring 252</entry></row><row><entry /><entry>Control System</entry></row><row><entry /><entry>central controller 300</entry></row><row><entry /><entry>Methods and Operation</entry></row><row><entry /><entry namest="OFFSET" nameend="1" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>